Torque sensor incorporating an angular position sensor of a rotating element

Abstract

A torque sensor mounted on a rotating element in a motor vehicle, including at least one strain gauge and emitting an electrical signal as a function of the torsion experienced by the rotating element, the torque sensor having a moving part intended to be driven in rotation with the rotating element and including the strain gauge and a fixed part including a first printed circuit board. The torque sensor also acts as an angular-position sensor, the moving part bearing angularly distributed targets passing in succession past a first annular sector borne by the first board including a secondary receiver winding generating a sine signal, a secondary receiver winding generating a cosine signal, and a primary emitter winding inducing a voltage in the receiver windings.

The invention claimed is: 
     
       1. A torque sensor intended to be mounted on a rotating element in a motor vehicle, the torque sensor comprising:
 at least one strain gauge applied to an adhesive material layer, said at least one strain gauge emitting an electrical signal as a function of torsion experienced by the rotating element under the effect of a torque, the torque sensor having a moving part intended to be driven in rotation with the rotating element and comprising said at least one strain gauge, and 
 a fixed part comprising a first printed circuit board, 
 wherein the torque sensor also acts as an angular-position sensor, the moving part bearing angularly distributed targets passing in succession, as the moving part rotates, past a first annular sector borne by the fixed first printed circuit board, the first annular sector comprising at least a first annular secondary receiver winding designed to generate a sine signal as a target passes past it, at least a second secondary receiver winding designed to generate a cosine signal as a target passes past it and at least one annular primary emitter winding designed to induce an electrical voltage in said secondary receiver windings. 
 
     
     
       2. The torque sensor as claimed in  claim 1 , wherein etched into the fixed first printed circuit board are, on the one hand, at least one coil for measuring torque and making it possible to emit an alternating magnetic field, to power the moving part by induction, and to receive the electrical torque-measurement signal regarding the rotating element, and, on the other hand, in the first annular sector, at least three coils for measuring angular-position, at least one of which is a primary coil emitting an alternating magnetic field for the annular primary emitter winding and at least two of which are secondary coils etched inside said at least one primary coil for, respectively, the first secondary receiver winding and said at least one second secondary receiver winding, said at least one coil for the torque measurement and said at least one primary coil emitting at different respective frequencies. 
     
     
       3. The torque sensor as claimed in  claim 2 , wherein the fixed first printed circuit board is housed in a fixed reading member and divided into two concentric annular sectors with a second annular sector comprising said at least one coil for the torque measurement and being the outermost of the two annular sectors, the second annular sector receiving, via electronic receiving and processing means incorporated into the fixed reading member, a signal emitted by electromagnetic emission means of a rotary detection member housed in the moving part, the rotary detection member facing the fixed reading member. 
     
     
       4. The torque sensor as claimed in  claim 3 , wherein the adhesive material layer rests on one face of a substrate made of a rigid material able to ensure that it is held by friction against the rotating element via its opposite face to the one bearing the adhesive material layer, the moving part comprising pressure means surrounding the adhesive material layer and the substrate and being able to surround the rotating element and to press the opposite face of the substrate against the rotating element, the targets being borne either by the rotary detection member or by the pressure means, this being on a face that faces toward the fixed first printed circuit board. 
     
     
       5. The torque sensor as claimed in  claim 4 , wherein the targets are borne by a rotary second printed circuit board that forms part of the rotary detection member, each target being obtained by locally engraving the second printed circuit board with the depositing of a target-forming metallic layer. 
     
     
       6. The torque sensor as claimed in  claim 5 , wherein the pressure means are formed by two shell portions extending each other in order to form a complete shell, fixing means of the threaded rod type securing the two shell portions together, the two shell portions housing within them the substrate and the adhesive material layer, the rotary detection member being fixed against a circular exterior periphery of the two shell portions joined together. 
     
     
       7. The torque sensor as claimed in  claim 4 , wherein when the targets are borne by the pressure means, each target is obtained by machining or by the addition of metallic inserts. 
     
     
       8. The torque sensor as claimed in  claim 7 , wherein the pressure means are formed by two shell portions extending each other in order to form a complete shell, fixing means of the threaded rod type securing the two shell portions together, the two shell portions housing within them the substrate and the adhesive material layer, the rotary detection member being fixed against a circular exterior periphery of the two shell portions joined together. 
     
     
       9. The torque sensor as claimed in  claim 4 , wherein the pressure means are formed by two shell portions extending each other in order to form a complete shell, fixing means of the threaded rod type securing the two shell portions together, the two shell portions housing within them the substrate and the adhesive material layer, the rotary detection member being fixed against a circular exterior periphery of the two shell portions joined together. 
     
     
       10. The sensor as claimed in  claim 4 , wherein the fixed reading member and the rotary detection member are housed in a respective housing, each in the form of a ring, these respectively being fixed and mobile, which may or may not be incomplete, the fixed and mobile rings being spaced apart by a gap of predetermined dimension allowing wireless communication between the rings and a positioning of the targets with respect to the first printed circuit board that modifies the magnetic coupling between the primary winding and the two secondary windings when facing the first annular sector. 
     
     
       11. The sensor as claimed in  claim 10 , wherein the housing of the fixed reading member is aligned with the housing of the detection member along a longitudinal axis of rotation of the detection member, or the housing of the fixed reading member surrounds the housing of the detection member ( 10 ) from a distance. 
     
     
       12. The sensor as claimed in  claim 1 , wherein the targets are of roughly parallelepipedal shape with two, inner and outer, rounded faces intended to be concentric with the rotating element, the length of the inner rounded face being shorter than the length of the outer rounded face. 
     
     
       13. The torque sensor as claimed in  claim 1 , wherein said at least one strain gauge is in the form of a micro-electromechanical system with piezoresistive cells. 
     
     
       14. An assembly of a rotating element in a motor vehicle and a torque sensor, the torque sensor comprising:
 at least one strain gauge applied to an adhesive material layer, said at least one strain gauge emitting an electrical signal as a function of torsion experienced by the rotating element under the effect of a torque, the torque sensor having a moving part intended to be driven in rotation with the rotating element and comprising said at least one strain gauge, and 
 a fixed part comprising a first printed circuit board, 
 wherein the torque sensor also acts as an angular-position sensor, the moving part bearing angularly distributed targets passing in succession, as the moving part rotates, past a first annular sector borne by the fixed first printed circuit board, the first annular sector comprising at least a first annular secondary receiver winding designed to generate a sine signal as a target passes past it, at least a second secondary receiver winding designed to generate a cosine signal as a target passes past it and at least one annular primary emitter winding designed to induce an electrical voltage in said secondary receiver windings, and wherein the torque sensor. 
 
     
     
       15. The assembly as claimed in  claim 14 , wherein the rotating element is a transmission shaft or a flywheel.